What Is DNS? How the Internet Phone Book Works
By [FILL IN], [FILL IN] · Last updated
DNS turns names like example.com into IP addresses. A beginner-friendly explanation of resolvers, records, caching and why DNS matters for security.
Names to numbers
Computers connect using IP addresses. DNS, the Domain Name System, translates human-friendly names into those addresses.
The lookup journey
When you type a web address, your device asks a recursive resolver. If it does not have the answer cached, it asks the root servers, then the top-level domain servers (.com, .se), then the domain's authoritative servers.
Common record types
DNS stores more than addresses.
- A and AAAA: IPv4 and IPv6 addresses
- CNAME: an alias to another name
- MX: mail servers
- TXT: verification and email security (SPF, DKIM, DMARC)
- NS: which servers are authoritative
Why it matters for security
Whoever runs your resolver decides which answers you get. Choosing a filtering resolver turns every lookup into a security check.